Coupling coefficients for distributed feedback single- and double-heterostructure diode lasers

We compute coupling coefficients for TE modes as a function of tooth height, active layer thickness, and Bragg scattering order in single-heterostructure (SH) and double-hetetostructute (DH) distributed feedback (DFB) diode lasers for a variety of corrugation shapes. In particular, equations for rectangular, sinusoidal, and triangular shapes are evaluated; the last both in the symmetric and saw-tooth cases. It is shown that the coupling coefficient for rectangular and sawtooth gratings decreases much less rapidly with increasing Bragg order than do the sinusoidal and symmetric triangular.     

以模块为基础的薄带材和箔材平直度控制

薄带材和箔材的平直度或板形控制必然要求一定程度的模型化。这是由于轧钢工艺本身的复杂性所要求的。描述在轧制带卷前到形成良好初始平直度的最佳轧制程序表及在高平直度控制情况下生产带卷的过程中使用的模块。集中讨论在普通4辊铝薄带和箔材轧机上所用的平直度模块。     

The histostructure of the adrenal gland in the Campbell hamster after extirpation of a specific midventral gland]

The receptors for retinoic acid (RA) and for 1 alpha,25-dihydroxyvitamin D3 (VD), RAR, RXR, and VDR are ligand-inducible members of the nuclear receptor superfamily. These receptors mediate their regulatory effects by binding as dimeric complexes to response elements located in regulatory regions of hormone target genes. Sequence scanning of the tumor necrosis factor-alpha type 1 receptor (TNF alpha RI) gene identified a 3' enhancer region composed of two directly repeated hexameric core motifs spaced by 2 nucleotides (DR2). On this novel DR2-type sequence, but not on a DR5-type RA response element, VD was shown to act through its receptor, the vitamin D receptor (VDR), as a repressor of retinoid signalling. The repression appears to be mediated by competitive protein-protein interactions between VDR, RAR, RXR, and possibly their cofactors. This VDR-mediated transrepression of retinoid signaling suggests a novel mechanism for the complex regulatory interaction between retinoids and VD.     

Root resorptions in upper first premolars after application of continuous intrusive forces. Intra-individual study

A scanning electron microscopy study of possible root resorptions and their localization after application of continuous forces of different magnitudes was conducted. Twelve upper first premolars, indicated for extraction, were previously intruded with constant forces. The teeth were divided into 3 groups: 1. non-moved control teeth, 2. continuous force application of 50 cN for 4 weeks, 3. continuous force application of 100 cN for 4 weeks. Specially designed NiTi-SE-stainless steel springs were utilized to exert the actual forces. After experimental tooth movement, the extracted teeth were dehydrated, metal-coated and examined by scanning electron microscopy. The intruded teeth showed resorptive areas consisting of lacunae (concavities) in the mineralized root surface. The teeth moved with 50 cN showed in the apical third several, in the medial third few, and in the cervical third no resorptive areas. In the case of the teeth moved with 100 cN, we observed resorptive areas in most of the apical third--including the apex contour-, several in the medial third, and none in the cervical third. In the control group no resorptions were observed. Thus, our results suggest that intrusion of human teeth with continuous forces induces root resorption, depending on the magnitude of force applied.     

Role of platelet-activating factor in long-term potentiation of the rat medial vestibular nuclei

In rat brain stem slices, we investigated the role of platelet activating factor (PAF) in long-term potentiation (LTP) induced in the ventral part of the medial vestibular nuclei (MVN) by high-frequency stimulation (HFS) of the primary vestibular afferent. The synaptosomal PAF receptor antagonist, BN-52021 was administered before and after HFS. BN-52021 did not modify the vestibular potentials under basal conditions, but it reduced the magnitude of potentiation induced by HFS, which completely developed after the drug wash-out. The same effect was obtained by using CV-62091, a more potent PAF antagonist at microsomal binding sites, but with concentrations higher than those of BN-52021. By contrast both BN-52021 and CV-6209 had no effect on the potentiation once induced. This demonstrates that PAF is involved in the induction but not in the maintenance of vestibular long-term effect through activation of synaptosomal PAF receptors. In addition, we analyzed the effect of the PAF analogue, 1-O-hexadecyl-2-O- (methylcarbamyl)-sn-glycero-3-phosphocoline (MC-PAF) and the inactive PAF metabolite, 1-O-hexadecyl-sn-glycero-3-phosphocoline (Lyso-PAF) on vestibular responses. Our results show that MC-PAF, but not Lyso-PAF induced potentiation. This potentiation was prevented by D,L-2-amino 5-phosphonopentanoic acid, suggesting an involvement of N-methyl-D-aspartate receptors. Furthermore, under BN-52021 and CV-6209, the MC-PAF potentiation was reduced or abolished. The dose-effect curve of MC-PAF showed a shift to the right greater under BN-52021 than under CV-6209, confirming the main dependence of MC-PAF potentiation on the activation of synaptosomal PAF receptors. Our results suggest that PAF can be released in the MVN after the activation of postsynaptic mechanisms triggering LTP, and it may act as a retrograde messenger which activates the presynaptic mechanisms facilitating synaptic plasticity.     

Solubility thermodynamics of amine boranes in polar solvents

Amine boranes are solid hydrogen storage materials and are difficult to transport within systems unless dissolved in solvents. The solubility and free energy of solution were experimentally determined for ammonia borane, methylamine borane, dimethylamine borane, trimethylamine borane, and tert-butylamine borane in methanol, ethanol, 1-propanol, 2-propanol, acetonitrile, dimethyl sulfoxide, and tetrahydrofuran. The solubilities of ammonia borane/methylamine borane mixtures in methanol were also measured. The enthalpy of solution was experimentally determined for ammonia borane, methylamine borane, dimethylamine borane, and 30/70 wt% ammonia borane/methylamine borane eutectic in four different solvents: methanol, ethanol, acetonitrile, and dimethyl sulfoxide. For all solutes, dimethyl sulfoxide solutions were the most exothermic or least endothermic. Increased methyl-substitution on the amine led to more endothermic processes. For methanol, ethanol, and acetonitrile, the entropy of solution increased as solubility increased. The entropy of solution for ammonia borane dissolving in dimethyl sulfoxide is negative. COSMO-RS solubility calculations using density functional theory optimized geometries agree relatively well with experimental values for amine borane materials dissolved in polar solvents.     

Reversibility of Schistosoma mansoni-associated morbidity after yearly mass praziquantel therapy: ultrasonographic assessment

OBJECTIVE: To study the outcome of osteoporosis assessment and rehabilitation in post-fracture patients. METHODS: This was a retrospective survey of the records of patients who had been referred to us from orthopaedic departments for rehabilitation after a fracture. RESULTS: A significant number of patients had had previous fractures (n = 17) or risk factors for osteoporosis (n = 16). The mortality rate was 4%. A significant proportion of patients (9/44) who had been living in their homes required placement in residential or nursing homes and additional care after rehabilitation. CONCLUSION: Our audit showed that post-fracture patients received optimum care, as set out in the Royal College of Physicians guidelines, but could benefit additionally from assessment and treatment of osteoporosis as set out in the Department of Health (DOH) Guidelines.     

Pyrolysis kinetics for Green River oil shale from the saline zone

The nature of the organic and mineral reactions during the pyrolysis of Saline-zone Colorado oil shale containing large amounts of nahcolite and dawsonite has been determined. Results reported include a material-balanced Fischer assay and measurements of gas evolution rate of CH₄, C₂H_x, H₂, CO and CO₂, Stoichiometry and kinetics of the organic pyrolysis reactions are similar to oil shale from the Mahogany zone. X-ray diffraction and thermogravimetric analysis results are used to help determine the characteristics of the mineral reactions. Kinetic expressions are reported for dawsonite decomposition, and it is demonstrated that the temperature of dolomite decomposition is substantially lower than for Mahogany-zone shale because of the presence of the sodium minerals.     

Dezentrale Energieversorgung unter besonderer Berücksichtigung von PEM-Brennstoffzellen

After an overview the phases of the development of the electrical power supply, the differences of the power supply structures and the reasons for these are discussed. The liberalization of the electricity market in Europe will offer increased opportunities for decentralised power supply in the future. An installation which is based on PEM fuel cells with an output power of 250 kW for the decentralized provision of electricity and heat from natural gas is introduced. Furthermore, the economic boundary conditions for the coupled generation of electricity and heat are discussed.